With the development of electronics industries, a demand for a printed wiring board for mounting electronic devices such as an IC (integrated circuit) or an LSI (large scale integrated circuit) has suddenly increased and a reduction in the size and weight and an increase in the function of an electronic equipment have been required. As a method of mounting electronic devices which meets these requirements, there has recently been employed a mounting method using a film carrier tape such as a TAB tape, a T-BGA tape and an ASIC tape. In particular, the importance has been increased in the electronic industries which use a liquid crystal display (LCD) requiring an enhancement in fineness, a reduction in thickness and a decrease in the frame area of a liquid crystal screen as in a personal computer or the like.
FIG. 6 shows an example of the structure of the TAB tape which has conventionally been used generally. A TAB tape 110 has a plurality of sprocket holes 112 and 114 for conveyance of the tape arranged continuously in a longitudinal direction on both side ends in a transverse direction respectively and a device hole 116 for attaching a device such as an IC is formed in an almost central portion between the sprocket holes 112 and 114 There is formed a wiring pattern 122 in which an inner lead 118 in the device hole 116 and an outer lead 120 are connected to each other.
The TAB tape is usually manufactured in the following manner. A copper foil is laminated, to a base material film such as a polyimide film having an adhesive applied onto a surface of the base material film. Then the surface of the copper foil is coated with a photoresist. For the photoresist surface, a portion other than a copper wiring pattern to be formed is exposed and the exposed photoresist is removed. Next, a copper foil in the portion from which the photoresist has been removed is removed by etching, and furthermore, the photoresist is removed so that the copper wiring pattern is formed. Alternatively, the copper wiring pattern portion to be formed is exposed and a photoresist which is not exposed is removed from a resist surface depending on the type of the photoresist to be used. Then, the copper foil in the portion in which the photoresist has been removed is removed by the etching, and furthermore, the photoresist is removed so that the copper wiring pattern is formed.
A solder resist to be a protective layer for a circuit is applied onto a tape on which the wiring pattern is thus formed excluding the connecting portion of the inner lead and the like. After the applied solder resist is cured, a plated layer such as tin is formed on the connecting terminal portion.
After such a manufacturing process is carried out, a quality inspection for a wiring pattern defect or the like is executed for each mounting unit arranged on the TAB tape. More specifically, for example, there has been executed a human visual inspection (a transmitted light inspection or the like), a method described in Japanese Laid-Open Patent Publication No. 6-174774 for electrically inspecting an electrical disconnection of a wiring pattern, a short circuit and an insulation resistance, or the like.
As a result of the quality inspection, a defect mark is given to a mounting unit determined to be defective. Examples of a marking method of giving a defect mark include a method of forming a punching hole on a defective unit or a method of carrying out ink marking over a defective unit by means of a stamp member. The position of the defect marking is varied for each product.
The TAB tape over which the defect marking is thus carried out is shipped in such a state that it is wound upon a reel. At this time, a series of mounting units arranged on the TAB tape include a large number of normal pattern units and a few defective units (over which the marking is carried out).
On the other hand, recently, there have also been used tapes having no device hole, for example, a TAB tape for connecting an IC substrate, or the like with a solder ball through a hole opened on the TAB tape in place of an outer lead which is referred to as a BGA (Ball Grid Array) and a TAB tape including a package having the same size as the size of an IC and mainly having the same connecting method as that of the BGA which is referred to as a CSP (Chip Size Package) in addition to the TAB tape shown in FIG. 6.
Moreover, a mounting technique referred to as a COF (Chip on Film) has also been used as an effective technique for an increase in the density of a wiring pitch. The COF uses a two-layer tape having a polyimide layer and a copper foil provided without an adhesive layer which is manufactured by a casting method of coating an electrodeposited copper foil with a polyimide material and performing a heat treatment to form a polyimide film having a copper foil, or a plating method of forming a copper foil on the polyimide film by electrolytic plating.
FIG. 7 shows an example of the structure of a conventional COF tape. A COF tape 210 has a plurality of sprocket holes 212 and 214 for conveyance of the tape arranged continuously in a longitudinal direction on both side ends in a transverse direction respectively and a device such as an IC is mounted to an almost central portion 216 between the sprocket holes 212 and 214, for example. There is formed a wiring pattern 222 in which an inner lead 218 and an outer lead 220 on the film are connected to each other.
The COF tape is excellent in a heat resistance or the like in an IC mounting processing and has such a structure that a device hole is not formed but an inner lead is held by the film, and the IC is mounted on the film (not on the device hole).
Referring to these kinds of film carrier tapes for mounting electronic devices thereon, similarly, a manufacturing process for the formation of a wiring pattern or the like is carried out and a quality inspection is then performed for a wiring pattern defect on the film carrier tape or the like. More specifically, for example, there has been carried out a human visual inspection or a method described in Japanese Laid-Open Patent Publication No. 7-110863 in which the image of a wiring pattern formed on the COF tape is picked up by using a CCD camera referred to as a line sensor camera and image pick-up information thus obtained is compared with prestored data on the master pattern of a good product to inspect the defect of the wiring pattern.
As a result of the quality inspection, a defect mark is given to a mounting unit determined to be defective and the film carrier tape over which a defect display is carried out is wound upon a reel and is shipped in this condition.
The defect marking is to be carried out in a predetermined shape in a predetermined portion specified by a user of an electrical manufacturer according to the specification of the user who mounts a device such as an IC on the film carrier tape. More specifically, the film carrier tape is shipped to the user in such a state as to include a few defective units (which are marked) together with a large number of normal mounting units arranged on the tape as described above. When the user is to mount devices such as the IC on mounting units in the film carrier tape, there is an inconvenience that a mounting unit is not normally recognized to be a defective product but is mounted if a mark for defective recognition is not placed in a constant position.
In the film carrier tape for mounting electronic devices thereon!provided with a predetermined hole such as a device hole shown in FIG. 6 which has conventionally been used widely, an alignment is carried out by setting the device hole to be a reference of viewing when the defect marking is to be carried out. For example, a larger punching hole than the device hole 116 is formed in a position including the device hole 116 in FIG. 6. Thus, the alignment is simple and the defect marking can easily be carried out correctly in a predetermined position with high precision.
However, a film carrier tape to be used for a BGA, a CSP and a COF has no hole such as the device hole. For this reason, a defective recognition mark cannot be given based on an object to be a simple reference for the alignment.
As described above, it is necessary to correctly carry out the defect marking with high precision in a position specified by a user for each product. In some cases in which there is no simple reference, precision in the position of the defect marking is deteriorated or a marking position is grasped erroneously and the marking is carried out in a different position from the position specified by the user. In some cases, particularly, various products are actually manufactured at the same time and it is necessary to simultaneously correspond to various different specifications for products. Therefore, there is a particularly high possibility that the marking precision might be deteriorated or the marking position might be recognized erroneously.